/Engine/Plugins/Interchange/Runtime/Source/Import/Public/MaterialX/MaterialXUtils/MaterialXBase.h
Retrieve the input from a surfaceshader node, or take the default input from the library, this function should only be called after testing the MaterialX libraries have been successfully imported, meaning the node definition of the surfaceshader should always be valid
the input from the given name
MaterialX::InputPtr GetInput ( MaterialX::NodePtr Node, const char * InputName )